In the wee small hours of Monday morning, mates Falstaff Dowling-Mitchell and Aaron Ellis were "stoked" to finish the longest continual row on indoor machines after four days, 15 hours and seven minutes.

Their fundraising challenge took them one hour and seven minutes past the previous tandem continual row record, set by two Frenchmen in January 2013.

It was a surreal feeling, Dowling-Mitchell said.

"We were just giggling like schoolgirls more than anything, when we had a private moment to do that.

"He [Aaron] just looked at me and started cracking up and goes ‘We cracked a worldy' and he was laughing his head off," he said.

"We just could not believe we'd made it. Although we knew we'd never ever stop until something happened that we just couldn't carry on, we thought that would very possibly happen. We didn't know how our bodies would stack up."

Soreness and a queasy feeling soon set in to remind them what they had done, so after a couple of beers they headed home to bed.

Dowling-Mitchell slept for 11 hours, but heard that Ellis woke at 5am wondering where he was and when he was meant to be on the rower.

Their marathon fundraiser began in the staffroom of Te Totara Primary School at 9am on January 15, after about eight months of training.

Primary teacher Dowling-Mitchell rowed to raise money for Home of Hope partner Project Neema, which is aiming to build a primary school in Tanzania.

Bricklayer and dog-lover Ellis chose Paw Justice, which works to reduce animal abuse.

They took alternate shifts on the rowing machine for the duration, and the machine was not allowed to stop moving.

So the record-breakers relied on their "amazing" seven-person support crew, who took eight-hour shifts to be on hand 24/7 to film evidence for the record, encourage the men, make them food and wake them up in time to get back on the rower.

"We needed to be slapped and told to get our arse out of bed and get back out there, and woken three times sometimes."

The days turned into a blur, Dowling-Mitchell said.

"If someone had tricked me or there hadn't been a clock I just wouldn't even know how to begin to guess how much time had gone by," he said.

"It was just a cycle of eight sleeps a day, eight shifts on the rower a day, for four and a half days, night and day. You just got more and more tired and weak as it went on. I don't think we could have lasted another night."

While neither of the men is keen to get back on a rowing machine for some time, they are already considering another project - an ocean row between New Zealand and Australia.